The data on residence 1 year ago were derived from answers to Question 14, which were asked of the population 1 year and older. For the American Community Survey, people who had moved from another residence in the United States or Puerto Rico 1 year earlier were asked to report the exact address (number and street name); the name of the city, town, or post office; the name of the U.S. county or municipio in Puerto Rico; state or Puerto Rico; and the ZIP Code where they lived 1 year ago. People living outside the United States and Puerto Rico were asked to report the name of the foreign country or U.S. Island Area where they were living 1 year ago.
For the Puerto Rico Community Survey, people who moved from another residence in Puerto Rico or the United States 1 year ago were asked to report the exact address, including the development or condominium name; the name of the city, town, or post office; the municipio in Puerto Rico (county equivalent) or county in the U.S.; and the ZIP Code where they lived. People living outside Puerto Rico and the United States were asked to report the name of the foreign country or U.S. Island Area where they were living 1 year ago.

Residence 1 year ago is used in conjunction with location of current residence to determine the extent of residential mobility of the population and the resulting redistribution of the population across the various states, metropolitan areas, and regions of the country.

When no information on previous residence was reported for a person, information for other family members, if available, was used to assign a location of residence 1 year ago. All cases of nonresponse or incomplete response that were not assigned a previous residence based on information from other family members were allocated the previous residence of another person with similar characteristics who provided complete information.

The tabulation category, "Same house," includes all people 1 year and over who did not move during the 1 year as well as those who had moved and returned to their residence 1 year ago. The category, "Different house in the United States" includes people who lived in the United States 1 year ago but in a different house or apartment from the one they occupied at the time of interview. These movers are then further subdivided according to the type of move.

In most tabulations, movers within the U.S. are divided into three groups according to their previous residence: "Different house, same county," "Different county, same state," and "Different state." The last group may be further subdivided into region of residence 1 year ago. An additional category, "Abroad," includes those whose previous residence was in a foreign country, Puerto Rico, American Samoa, Guam, the Northern Marianas, or the U.S. Virgin Islands, including members of the Armed Forces and their dependents. Some tabulations show movers who were residing in Puerto Rico or one of the U.S. Island Areas 1 year ago separately from those residing in foreign countries.
In most tabulations, movers within Puerto Rico are divided into two groups according to their residence 1 year ago: "Same municipio," and "Different municipio." Other tabulations show movers within or between metropolitan areas similar to the stateside tabulations.

The characteristics of movers may be shown using either current residence-based or previous residence-based geography. If you are interested in the number and characteristics of movers living in a specific area, you should use the standard (residence-based) tables. If you are interested in the number and characteristics of movers who previous residence was in a specific area, you should use the residence-1-year-ago-based tables. Because residence-1-year-ago information for movers cannot always be specified below the place level, the previous residence-based tables are presented only for selected geographic areas.

Beginning in 2006, the group quarters (GQ) population is included in the ACS. Some types of GQ populations have residence one year ago (migration) distributions that are different from the household population. The inclusion of the GQ population could therefore have a noticeable impact on the residence one year ago (migration) distribution. This is particularly true for areas with a substantial GQ population.

The 1996-1998 questions asked about residence 5 years ago. Beginning in 1999, the time period was changed to that of 1 year ago, which reflects the on-going data collection on the American Community Survey, and allows for annual estimates of migration. Beginning in 1999, a separate write-in line and a skip instruction were added for a foreign country response. This write-in line was moved to one of the answer categories for the residence one year ago question. The migration parts (city, county, and state response areas) were also reordered. Beginning in 2003, the numerical order was changed so that part c of this question would not be displayed in a separate column of the questionnaire. Beginning with 2008, a write-in space for street address was included and the questions were reworded on both the ACS and the PRCS so that the geographic specificity is maintained for movers within and between the U.S. and Puerto Rico. Municipio of previous residence in Puerto Rico is available for people living in the United States as a result of this change.

Excerpt from:

Social Explorer; U.S. Census Bureau; American Community Survey 2006-2008 Summary File: Technical Documentation.

The U.S. Census Bureau treats the Commonwealth of Puerto Rico as the statistical equivalent of a state for data presentation purposes. Each state and statistically equivalent entity is assigned a two-digit Federal Information Processing Standards (FIPS) code in alphabetical order by state name, followed in alphabetical order by Puerto Rico and the Island Areas. Each state and statistically equivalent entity also is assigned the two-letter FIPS/U.S. Postal Service code.

The primary legal divisions of Puerto Rico are termed "municipios." For data presentation purposes, the U.S. Census Bureau treats a municipio as the equivalent of a county in the United States.
Each municipio is assigned a unique three-digit Federal Information Processing Standards (FIPS) code in alphabetical order within Puerto Rico.

The U.S. Census Bureau recognizes barrios and barrios-pueblo as the primary legal divisions of municipios. These entities are similar to the minor civil divisions (MCDs) used for reporting decennial census data in 28 states of the United States. Subbarrios in 23 municipios are the primary legal subdivisions of the barrios-pueblo and some barrios. The U.S. Census Bureau presents the same types of Census 2000 data for these "sub-MCDs" as it does for the barrios and barriospueblo. (There is no geographic entity in the United States equivalent to the subbarrio.) Each barrio, barrio-pueblo, and subbarrio is assigned a five-digit Federal Information Processing Standards (FIPS) code in alphabetical order within Puerto Rico.

There are no incorporated places in Puerto Rico; instead, the U.S. Census Bureau provides decennial census data for two types of census designated places (CDPs): (1) zonas urbanas, representing the governmental center of each municipio, and (2) comunidades, representing other settlements. For Census 2000, there are no minimum population size requirements for CDPs. (For the 1990 census, the U.S. Census Bureau had required comunidades to have at least 1,000 people.)

Each zona urbana and comunidad is assigned a five-digit Federal Information Processing Standards (FIPS) code in alphabetical order within Puerto Rico.

Some types of geographic entities do not apply in Puerto Rico. For instance, Puerto Rico is not in any census region or census division. In addition, the U.S. Census Bureau does not tabulate data for state legislative districts and traffic analysis zones in Puerto Rico. (See also CONGRESSIONAL DISTRICT (CD).)

Excerpt from:

Social Explorer; U.S. Census Bureau; American Community Survey 2006-2008 Summary File: Technical Documentation.

There are both legal and statistical American Indian, Alaska Native, and native Hawaiian entities for which the U.S. Census Bureau provides data for Census 2000. The legal entities consist of federally recognized American Indian reservations and off-reservation trust land areas, the tribal subdivisions that can divide these entities, state recognized American Indian reservations, Alaska Native Regional Corporations, and Hawaiian home lands. The statistical entities are Alaska Native village statistical areas, Oklahoma tribal statistical areas, tribal designated statistical areas, and state designated American Indian statistical areas. Tribal subdivisions can exist within the statistical Oklahoma tribal statistical areas.

In all cases, these areas are mutually exclusive in that no American Indian, Alaska Native, or Hawaiian home land can overlap another tribal entity, except for tribal subdivisions, which subdivide some American Indian entities, and Alaska Native village statistical areas, which exist within Alaska Native Regional Corporations. In some cases where more than one tribe claims jurisdiction over an area, the U.S. Census Bureau creates a joint use area as a separate entity to define this area of dual claims. The following provides more detail about each of the various American Indian areas, Alaska Native areas, and Hawaiian home lands.

Alaska Native Regional Corporations (ANRCs) are corporate entities established to conduct both business and nonprofit affairs of Alaska Natives pursuant to the Alaska Native Claims Settlement Act of 1972 (Public Law 92-203). Twelve ANRCs are geographic entities that cover most of the state of Alaska (the Annette Island Reserve-an American Indian reservation-is excluded from any ANRC). (A thirteenth ANRC represents Alaska Natives who do not live in Alaska and do not identify with any of the 12 corporations; the U.S. Census Bureau does not provide data for this ANRC because it has no geographic extent.) The boundaries of ANRCs have been legally established. The U.S. Census Bureau offers representatives of the 12 nonprofit ANRCs the opportunity to review and update the ANRC boundaries. The U.S. Census Bureau first provided data for ANRCs for the 1990 census.

Each ANRC is assigned a five-digit Federal Information Processing Standards (FIPS) code, which is assigned in alphabetical order by ANRC name.

Alaska Native village statistical areas (ANVSAs) are statistical entities that represent the densely settled portion of Alaska Native villages (ANVs), which constitute associations, bands, clans, communities, groups, tribes or villages, recognized pursuant to the Alaska Native Claims Settlement Act of 1972 (Public Law 92-203). ANVSAs are reviewed and delineated by officials of the ANV (or officials of the Alaska Native Regional Corporation (ANRC) in which the ANV is located if no ANV official chooses to participate in the delineation process) solely for data presentation purposes. An ANVSA may not overlap the boundary of another ANVSA, an American Indian reservation, or a tribal designated statistical area. The U.S. Census Bureau first provided data for ANVSAs for the 1990 census.

Each ANVSA is assigned a national four-digit census code ranging from 6000 through 7999. Each ANVSA also is assigned a state-based five-digit Federal Information Processing Standards (FIPS) code. Both the census and FIPS codes are assigned in alphabetical order by ANVSA name.

Federal American Indian reservations are areas that have been set aside by the United States for the use of tribes, the exterior boundaries of which are more particularly defined in the final tribal treaties, agreements, executive orders, federal statutes, secretarial orders, or judicial determinations. The U.S. Census Bureau recognizes federal reservations as territory over which American Indian tribes have primary governmental authority. These entities are known as colonies, communities, pueblos, rancherias, ranches, reservations, reserves, villages, Indian communities, and Indian villages. The Bureau of Indian Affairs maintains a list of federally recognized tribal governments. The U.S. Census Bureau contacts representatives of American Indian tribal governments to identify the boundaries for federal reservations.

Some state governments have established reservations for tribes recognized by the state. A governor-appointed state liaison provides the names and boundaries for state recognized American Indian reservations to the U.S. Census Bureau. The names of these reservations are followed by "(State)" in census data presentations.
Federal reservations may cross state boundaries, and federal and state reservations may cross county, county subdivision, and place boundaries. For reservations that cross state boundaries, only the portions of the reservations in a given state are shown in the data products for that state. Lands that are administered jointly and/or are claimed by two tribes, whether federally or state recognized, are called "joint use areas," and are treated as if they are separate American Indian reservations for data presentation purposes. The entire reservations are shown in data products for the United States. The U.S. Census Bureau first provided data for American Indian reservations in the 1970 census.
Each federal American Indian reservation is assigned a four-digit census code ranging from 0001 through 4999. These census codes are assigned in alphabetical order of American Indian reservation names nationwide, except that joint use areas appear at the end of the code range. Each state American Indian reservation is assigned a four-digit census code ranging from 9000 through 9499. Each American Indian reservation also is assigned a five-digit Federal Information Processing Standards (FIPS) code; because FIPS codes are assigned in alphabetical sequence within each state, the FIPS code is different in each state for reservations that include territory in more than one state.

Trust lands are areas for which the United States holds title in trust for the benefit of a tribe (tribal trust land) or for an individual Indian (individual trust land). Trust lands can be alienated or encumbered only by the owner with the approval of the Secretary of the Interior or his/her authorized representative. Trust lands may be located on or off of a reservation. The U.S. Census Bureau recognizes and tabulates data for reservations and off-reservation trust lands because American Indian tribes have primary governmental authority over these lands. Primary tribal governmental authority generally is not attached to tribal lands located off the reservation until the lands are placed in trust.

In the U.S. Census Bureau's data tabulations, off-reservation trust lands always are associated with a specific federally recognized reservation and/or tribal government. Such trust lands may be located in more than one state. Only the portions of off-reservation trust lands in a given state are shown in the data products for that state; all off-reservation trust lands associated with a reservation or tribe are shown in data products for the United States. The U.S. Census Bureau first provided trust land data for off-reservation tribal trust lands in the 1980 census; in 1990, the trust land data included both tribal and individual trust lands. The U.S. Census Bureau does not identify restricted fee land or land in fee simple status as a specific geographic category.

In decennial census data tabulations, off-reservation trust lands are assigned a four-digit census code and a five-digit Federal Information Processing Standards (FIPS) code that is the same as that for the reservation with which they are associated. As with reservations, FIPS codes for offreservation trust lands are unique within state, so they will differ if they extend into more than one state. The FIPS codes for such off-reservation trust lands are the same as those for the associated reservation. In the TIGER/Line® products, a letter code-" T" for tribal and "I" for individual- identifies off-reservation trust lands. In decennial census data tabulations, a trust land flag uniquely identifies off-reservation trust lands. Printed reports show separate tabulations for all off-reservation trust land areas, but do not provide separate tabulations for the tribal versus individual trust lands. Trust lands associated with tribes that do not have a reservation are presented and coded by tribal name, interspersed alphabetically among the reservation names.

American Indian tribal subdivisions are administrative subdivisions of federally recognized American Indian reservations, off-reservation trust lands, or Oklahoma tribal statistical areas (OTSAs), known as areas, chapters, communities, or districts. These entities are internal units of self-government or administration that serve social, cultural, and/or economic purposes for the American Indians on the reservations, off-reservation trust lands, or OTSAs.

The U.S. Census Bureau obtains the boundary and name information for tribal subdivisions from tribal governments. The U.S. Census Bureau first provided data for American Indian tribal subdivisions in the 1980 census when it identified them as "American Indian subreservation areas." It did not provide data for these entities in conjunction with the 1990 census.

Each American Indian tribal subdivision is assigned a three-digit census code that is alphabetically in order and unique within each reservation, associated off-reservation trust land, and OTSA. Each tribal subdivision also is assigned a five-digit Federal Information Processing Standards (FIPS) code. FIPS codes are assigned alphabetically within state; the FIPS codes are different in each state for tribal subdivisions that extend into more than one state.

Hawaiian home lands (HHLs) are areas held in trust for native Hawaiians by the state of Hawaii, pursuant to the Hawaiian Homes Commission Act of 1920, as amended. The U.S. Census Bureau obtained the names and boundaries of HHLs from state officials. HHLs are a new geographic entity for Census 2000.
Each HHL area is assigned a national four-digit census code ranging from 5000 through 5499 based on the alphabetical sequence of each HHL name. Each HHL also is assigned a five-digit Federal Information Processing Standards (FIPS) code in alphabetical order within the state of Hawaii.

Oklahoma tribal statistical areas (OTSAs) are statistical entities identified and delineated by the U.S. Census Bureau in consultation with federally recognized American Indian tribes in Oklahoma that do not currently have a reservation, but once had a reservation in that state. Boundaries of OTSAs will be those of the former reservations in Oklahoma, except where modified by agreements with neighboring tribes for data presentation purposes. OTSAs replace the "tribal jurisdiction statistical areas" of the 1990 census. The U.S. Census Bureau first provided data for the former Oklahoma reservations in conjunction with the 1980 census, when it defined a single allencompassing geographic entity called the "Historic Areas of Oklahoma (excluding urbanized areas)."

Each OTSA is assigned a national four-digit census code ranging from 5500 through 5999 based on the alphabetical sequence of each OTSAs name, except that the joint use areas appear at the end of the code range. Each OTSA also is assigned a five-digit Federal Information Processing Standards (FIPS) code in alphabetical order in Oklahoma.Opar

State designated American Indian statistical areas (SDAISAs) are statistical entities for state recognized American Indian tribes that do not have a state recognized land base (reservation). SDAISAs are identified and delineated for the U.S. Census Bureau by a state liaison identified by the governor's office in each state. SDAISAs generally encompass a compact and contiguous area that contains a concentration of people who identify with a state recognized American Indian tribe and in which there is structured or organized tribal activity. A SDAISA may not be located in more than one state unless the tribe is recognized by both states, and it may not include area within an American Indian reservation, off-reservation trust land, Alaska Native village statistical area, tribal designated statistical area (TDSA), or Oklahoma tribal statistical area. The U.S. Census Bureau established SDAISAs as a new geographic statistical entity for Census 2000, to differentiate between state recognized tribes without a land base and federally recognized tribes without a land base. For the 1990 census, all such tribal entities had been identified as TDSAs.

Each SDAISA is assigned a four-digit census code ranging from 9500 through 9999 in alphabetical sequence of SDAISA names nationwide. Each SDAISA also is assigned a five-digit Federal Information Processing Standards (FIPS) code in alphabetical order within state.

Tribal designated statistical areas (TDSAs) are statistical entities identified and delineated for the U.S. Census Bureau by federally recognized American Indian tribes that do not currently have a federally recognized land base (reservation or off-reservation trust land). A TDSA generally encompasses a compact and contiguous area that contains a concentration of people who identify with a federally recognized American Indian tribe and in which there is structured or organized tribal activity. A TDSA may be located in more than one state, and it may not include area within an American Indian reservation, off-reservation trust land, Alaska Native village statistical area, state designated American Indian statistical area (SDAISA), or Oklahoma tribal statistical area. The U.S. Census Bureau first reported data for TDSAs in conjunction with the 1990 census, when both federally and state recognized tribes could identify and delineate TDSAs. TDSAs now apply only to federally recognized tribes. State recognized tribes without a land base, including those that were TDSAs in 1990, are identified as SDAISAs, a new geographic entity for Census 2000.

Each TDSA is assigned a four-digit census code ranging from 8000 through 8999 in alphabetical sequence of TDSA names nationwide. Each TDSA also is assigned a five-digit Federal Information Processing Standards (FIPS) code in alphabetical order within state; because FIPS codes are assigned within each state, the FIPS code is different in each state for TDSAs that extend into more than one state.